激光冲击诱发薄壁零件微结构/应力场的演变机制及其稳定方法

Laser shock peening (LSP) is a newly developed innovative surface treatment technology, and can significantly improve the fatigue resistance of metallic materials, and receives widely attention since its birthday, because it can produce high amplitude residual compressive stress and seriously deformed microstructure layer which is deeper than 1mm. However, macro-deformation failure is easily appeared by the introduced residual stress field, and microstructure crack is easily induced by the superimposed interference of ultra-high-speed ultra-strong strain wave during the thin-walled metallic parts laser shock peening process, and the introduced residual compress stress and microstructure is easily relaxation and degradation under alternating loads and thermal cycles, thereby it constrains the laser shock peening technology using in aero-engine blades and other thin-walled parts. Therefore, to solve the above problems in the thin-walled parts laser shock peening process, based on the clearly understanding of laser shock induced microstructure and stress field evolution, the formation and evolution mechanism of laser shock ultrahigh strain rate plastic deformation induced microstructure and residual stress is revealed, the principles of microstructure and residual stress field stability is explored, controlled residual stress field and stabled microstructure are got by controlling material flow stress and easing ultra-fast strain wave, and the thin-walled parts laser shock peening technical bottleneck is finally breakthrough.

新近发展的激光冲击强化技术，因其能在材料表面引入厚度超过1mm的微观组织形变层和残余压应力层，能大幅提升金属零件的服役寿命，自产生之日起便引起了广泛的关注。然而，薄壁零件在激光冲击强化过程中易因引入的残余应力场造成宏观变形失效、易因超高速超高强应变波波峰的叠加干涉诱发内部组织开裂，以及产生的残余压应力和微结构在交变应力与热循环作用下易发生松弛和退化，从而制约了激光冲击强化技术在航空发动机叶片等薄壁零件中的应用。因此，针对薄壁零件激光冲击强化中出现的上述问题，本课题提出在明晰激光冲击诱导微结构演化和应力场演变过程的基础上，揭示激光冲击超高应变率塑性变形诱发的微结构和残余应力的形成演化机制、探索微结构和残余应力场的稳定原理，通过调控材料流变应力与疏导超高速应变波的方式调控残余应力场、稳固微观组织结构，最终突破薄壁零件激光冲击强化的技术瓶颈。

新近发展的激光冲击强化技术，因其能在材料表面引入厚度超过1mm的微观组织形变层和残余压应力层，能大幅提升金属零件的服役寿命，自产生之日起便引起了广泛的关注。然而，薄壁零件在激光冲击强化过程中易因引入的残余应力场造成宏观变形失效、易因超高速超高强应变波波峰的叠加干涉诱发内部组织开裂，以及产生的残余压应力和微结构在交变应力与热循环作用下易发生松弛和退化，从而制约了激光冲击强化技术在航空发动机叶片等薄壁零件中的应用。因此，针对薄壁零件激光冲击强化中出现的上述问题，本课题提出在明晰激光冲击诱导微结构演化和应力场演变过程的基础上，揭示激光冲击超高应变率塑性变形诱发的微结构和残余应力的形成演化机制、探索微结构和残余应力场的稳定原理，通过调控材料流变应力与疏导超高速应变波的方式调控残余应力场、稳固微观组织结构，总结出激光冲击超高应变率塑性变形诱发的微结构和残余应力的形成，演化机制、探索出微结构和残余应力场的稳定原理，提炼出科学问题共性技术，突破高性能薄壁件激光冲击强化的技术瓶颈。最终突破薄壁零件激光冲击强化的技术瓶颈。